[gameplay] Rework attack forge techs

Follow up to D3287/rP24604.

• Remove the specialised infantry/cavalry attack technologies, in favour of generalist melee/ranged techs to make it easier to switch army compositions.
• Lower the costs of the technologies substantially.
• Make melee techs cost Food/Metal and Ranged techs Wood/Metal, like resistance techs.
• City phase upgrades take 60s
• New names and descriptions for the ranged attack technologies.

Initial patch by @borg-, rebased and updated by @Nescio.

Differential Revision: https://code.wildfiregames.com/D3366